Having worked both part time and full time I found myself more exhausted on the part time schedule than my previous roster..
Part time was only offered to Capatins with more than 5 years in the company and really designed for those wishing to commute, or spend more consecutive days off at summer houses etc.
The issue we had was that as the FTLs were changed to EASA , the min days off changed to "min Rest between duties", this meant that I could work nearly 75% of my previous roster for 50% of the money.
We negotiated that "part timers" would finish their roster on an 'early " and start on a "late" this gave the max days off, however, the company required we be at "base" 24 hrs before the next schedule so that negated the advantage. The part time contract allowed for additional payments if pilots agreed to work "off days", however excluded compulsory days in the event of tech issues, so if you went AOG down route, all you got was more off days added, which we deemed fair.
Part timers had proportional holiday allowance and roster bidding, so no penalties there.
My employer regarded part time as an earned privilege not a right.